JPH04210133A - Ventilated type disc brake rotor - Google Patents

Abstract

PURPOSE:To reduce the wall thickness of each fin part of a disc brake rotor while maintaining the strength, by forming each disc part in the flake graphite cast-iron structure and the fin parts in the spherical graphite cast-iron structure. CONSTITUTION:Two mutually facing disc parts 1 are cast in consolidation with a plurality of fin parts 2 situated between these disc parts 1. These disc parts 1 and fin parts 2 have a composition containing 3.10-3.60wt.% C, 1.90-2.40wt.% Si, 0.5-0.8wt.% Mn, no more than 0.05wt.% P, no more than 0.01wt.% S, 0.005-0.010wt.% Mg, and Fe as remainder. The disc parts 1 have the flake graphite cast-iron structure, while the fin parts 2 have spherical graphite cast-iron structure. Thereby a ventilated type disc brake rotor is accomplished which can exert an improved braking performance while the strength is well maintained.

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in ventilated disc brake rotors used in disc brakes. [0002]

[Prior Art] In a disc brake, a disc brake rotor rotates together with the wheels of a vehicle, and when braking the vehicle, a disc brake caliper presses a disc brake pad against the lining of the disc brake rotor and disc brake pad. The vehicle is braked due to friction. At this time, if the cooling performance of the disc brake rotor is insufficient, the temperature of the disc brake pad increases, which induces unfavorable phenomena such as fade, premature wear of the lining, and brake vibration. Therefore, with the recent needs for higher output and improved handling stability of vehicles, there is a demand for improved cooling performance of the disc brake rotor. For this reason, at present, in response to such a demand, a ventilated type device consisting of two disc parts 91 facing each other and a plurality of fin parts 92 provided between each disc part 91 is being developed, as shown in FIG. It is widely used. [0003] Conventional ventilated disc brake rotors have a carbon content of 3.10 to 3 in consideration of wear resistance.
．． 60% by weight, silicon: 1.90-2.40% by weight, manganese: 0.5-0.8% by weight, phosphorus: 0.2% by weight or less, sulfur: 0.1% by weight or less, balance iron molten metal , that is, J
The disk portion 91 and each fin portion 92 were mainly manufactured by integrally casting the disk portion 91 and each fin portion 92 using a molten metal equivalent to ISFC20 gray cast iron. [0004] In this ventilated type, heat due to friction with the disc brake pad can be radiated through ventilation between the fin parts 92, so it has better cooling performance than the solid type made of one disc part, and the brake It can be said that it satisfies recent needs in terms of performance. [0005]

[Problems to be Solved by the Invention] However, since the conventional ventilated disc brake rotor (hereinafter referred to as a disc rotor) uses molten metal equivalent to JISFC20, it is difficult to reduce the thickness of the fin part. 4.5
~ If it is about 5mm or more, tensile strength: 20kg/
Although the fins can be formed using a flaky graphite cast iron structure with sufficient strength of mm2 or more, the wall thickness of the fins is 4.5mm.
If the thickness is less than about 5 mm, the thin-walled fin portion will cool faster than the thick-walled disk portion during casting, and the fin will only be formed in a eutectic graphite cast iron structure with a weak tensile strength of 10 kg/mm2 or less. cannot form a section. [0006] For this reason, in conventional disc rotors, the thickness of the fins is made thinner and the number of fins formed is increased in order to further radiate heat caused by friction through ventilation between the fins, in other words, to further improve cooling performance. Even if we tried to expand the radiating surface area, this was not possible due to the deterioration of strength, so by making the wall thickness of the fin part about 4.5 to 5 mm or more, the disk part and fin part were made of flaky graphite cast iron. This only ensured strength and maintained braking performance. [0007] The present invention has been made in view of the above-mentioned conventional demands, and an object of the present invention is to provide a disc rotor that can exhibit even better braking performance while maintaining strength. [0008]

[Means for Solving the Problems] The disc rotor of the present invention has been made as a result of intensive research by the inventor, and includes two
In a ventilated disc brake rotor in which two facing disc parts and a plurality of fin parts between the disc parts are integrally cast, each of the disc parts and the fin parts are made of carbon (C): 3. 10-3.60
Electrical capacity (hereinafter abbreviated as wt)%, silicon (S i):
1. 90-2゜40 wt%, manganese (Mn)
: 0.5-0.8wt%, phosphorus (P): 0.0
5wt% or less, sulfur (S): 0.01wt% or less, magnesium (Mg): 0. o. It has a composition of 5 to 0.010 wt%, the balance iron (Fe),
Further, the disk portion has a flaky graphite cast iron structure, and the fin portion has a spheroidal graphite cast iron structure. [0009] Each disk portion and fin portion has a C:3.1
0 to 3.60 wt%, Si: 1. 90-2.
40wt%, Mn: 0.5-0.8wt%, P: 0
．． 05wt% or less, S: 0.01wt% or less, Mg: 0
．． It can be manufactured by integrally casting the disk portion and each fin portion using a molten metal having a composition of 0.005 to 0.010 wt%, the balance being Fe. [00101 This molten metal is one in which P and S of JISFC20 are suppressed and Mg is added thereto. That is,
In this molten metal, P and S act as chilling promoting elements, so P exceeds 0.05 wt% or S exceeds 0.01 wt%.
If it exceeds wt%, the structure of each disk portion and fin portion becomes chilled, resulting in poor strength, wear resistance, and ductility. Furthermore, if the Mg content is less than 0.005 wt%, the fin portion will have a eutectic graphite cast iron structure, resulting in poor ductility and strength. If Mg exceeds 0.010 wt%, the disk portion as well as the fin portion will have a spheroidal graphite cast iron structure, resulting in poor strength and wear resistance. [00111 The thickness of the fin portion can be selected to be thinner than the conventional one in relation to the cooling rate. For example, in the case of air cooling to room temperature, the wall thickness can be set to 1 to 3 mm. If the wall thickness is less than 1 mm, it is difficult to cast, and if the wall thickness exceeds 3 mm, it is difficult to form a spheroidal graphite cast iron structure. [0012]

[Function] During casting, due to the molten metal having the above composition, graphite grows sufficiently in the disk part to form a flaky graphite cast iron structure, and the thin-walled fin part cools faster than the thick-walled disc part, causing spheroidal graphite to form in the fin part. It becomes a cast iron structure. The flake graphite cast iron structure of the disk part has sufficient strength and is particularly excellent in wear resistance, and the spheroidal graphite cast iron structure of the fin part has superior strength and ductility than the flake graphite cast iron structure. [0013] Therefore, in this disc rotor, it is possible to reduce the thickness of the fin part and increase the number of fins formed, so the radiation surface area is expanded and the heat caused by friction can be further transferred to the fin part. The ventilation between the two makes it easier to radiate air, further improving cooling performance. [0014]

[Example] Examples embodying the present invention will be described below with reference to the drawings together with Comparative Example Product 1.2. (1) Example product As an example product, C: 3.3wt%, Si: 2.2wt
%, Mn: 0.6wt%, P: 0.009wt%,
S: 0.006wt%, Mg: 0.007wt%,
As shown in FIG. 1, the disk part 1 and each fin part 2 were integrally cast using a molten metal having a composition of the remainder Fe, with the thickness t of the fin part 2 being 1.5 mm. Note that, at this time, a sand casting method using a core was adopted to form the fin portion 2. [0015] In the disc rotor thus manufactured, the radiation surface area between each disc part 1 is 3421. It was 1 mm2. Further, the disk portion 1 had a flaky graphite cast iron structure shown in FIG. 5, and the fin portion 2 had a spheroidal graphite cast iron structure shown in FIG. In addition, in this spheroidal graphite cast iron structure, the graphite particle size was about 10 μm, which was a finer structure than the general spheroidal graphite cast iron structure. (2) Comparative Example Product 1 As Comparative Example Product 1, C: 3.3wt%, Si: 2.2w
t%, Mn: 0.55wt%, P: 0.020wt
%, S: 0.032wt%, balance Fe JISFC20
Using a corresponding amount of molten metal, as shown in FIG. 4, the disk part 8 and each fin part 9 were assembled into one body, with the wall thickness t of the fin part 9 being 4.5 mm, and other conditions being the same as those of the example product. Cast. [0016] In the disc rotor thus manufactured, the radiation surface area between each disc portion 8 is 2556. 8mrn2
Met. Further, the disk portion 8 and the fin portion 9 had a flake graphite cast iron structure shown in FIG. (3) Comparative Example Product 2 As Comparative Example Product 2, JISFC20 is the same as Comparative Example Product 1.
Using a corresponding amount of molten metal, the disk part and each fin part were integrally cast under the same conditions as the example product, except that the thickness t of the fin part was 1.5 mm. [0017] In the disc rotor thus manufactured, the disc part had a flaky graphite cast iron structure shown in FIG. 5, but the fin part had a eutectic graphite cast iron structure shown in FIG. Layers were also appearing. (4) Evaluation In order to compare the cooling performance, using the example product and comparative example product 1, the vehicle speed (kg/hour) to the 0.8 power and the cooling coefficient bvX1
0-3 (1/sec) was determined. The results are shown in Figure 2. [00181 From FIG. 2, it can be seen that the example product has a greater number of formed fin portions than the comparative example product 1, so that the cooling performance is improved compared to the comparative example product 1. In addition, in order to compare the strength characteristics, the Example product and Comparative Example product 1 were used to measure changes in flatness, which can be used to evaluate brake vibration. This surface skin change was confirmed by testing the Example product and Comparative Example product 1 by heating it to 400°C and then cooling it with water to room temperature, and as shown in Figure 3, it was found that This was carried out by measuring the swing width (μm) before the test: x and the swing width (μm) after the test: y at position B 40 mm from the outer periphery. The results are shown in Table 1. [00191 Table 1 From Table 1, it can be seen that the Example product and Comparative Example Product 1 have substantially the same swing widths x and y at both the A position and the B position. Therefore, it can be seen that there is no change in the single strength characteristic even in the example product in which the thickness of the fin portion is reduced. [0020] Therefore, from the above evaluation, it can be seen that in the disc rotor of the example product, the cooling performance is further improved while maintaining the strength. It is also inferred that if the disc rotor of the example product is adopted, a more excellent disc brake can be obtained. [00211] [Effects of the Invention] As detailed above, in the disc rotor of the present invention, the disc part has a flaky graphite cast iron structure and the fin part has a spheroidal graphite cast iron structure, so that the fins can be formed while maintaining strength. The wall thickness of the part can be made thinner, and the number of parts formed can be increased. Therefore, with this disc rotor, the radiation surface area is expanded while maintaining the strength characteristics, and the heat caused by friction with the disc brake pad can be further radiated through ventilation between the fins, resulting in even better cooling performance. can demonstrate. [0022] Therefore, if this disc rotor is adopted as a component of a disc brake, in order to make it easier for outside air to come into contact with the disc brake, it is necessary to install an air duct, smooth the fender liner, etc. to free up space in the vehicle. Even better braking performance can be obtained without the need for equipment that requires reduction.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a disc brake rotor of an example product.

FIG. 2 is a graph showing a comparison of the characteristics of the example product and comparative example product 1.

FIG. 3 is a partial cross-sectional view of the disc brake rotor showing the measurement positions of flatness changes.

FIG. 4 is a partial sectional view of a disc brake rotor of Comparative Example Product 1.

FIG. 5 is a 100x micrograph showing a eutectic graphite cast iron structure, which is a metallographic structure of a disc brake rotor.

FIG. 6 is a 100x micrograph showing a spheroidal graphite cast iron structure, which is a metal structure of a disc brake rotor.

FIG. 7 is a perspective view showing a general ventilated disc brake rotor.

[Explanation of symbols]

1... Disc part 2...Fin part

Claims (1)

[Claims] 1. A ventilated disc brake rotor in which two facing disc parts and a plurality of fin parts between the disc parts are integrally cast, wherein each of the disc parts and the fin parts are made of carbon. :3.10~3.60
Weight%, silicon: 1.90-2.40% by weight, manganese:
0.5 to 0.8% by weight, phosphorus: 0.05% by weight or less, sulfur: 0.01% by weight or less, magnesium: 0.005
- 0.010% by weight, balance iron, and the disc portion has a flaky graphite cast iron structure, and the fin portion has a spheroidal graphite cast iron structure. brake rotor.